[MOIMS-NAV-EXEC] [EXTERNAL] Re: leap second flagging

[Daniel Oltrogge]

Cheryl –

One of the primary reasons (but not the only reason) for using relative time is to circumvent concerns about the introduction of leap seconds.

Wouldn’t they be able to use relative time and not worry (as much) about leap seconds?

Dan Oltrogge ҉ Director, Integrated Operations and Research ҉ COMSPOC Corporation  ҉ 719-482-4552 ҉ dan at comspoc.com<mailto:dan at comspoc.com>

From: Gramling, Cheryl J. (GSFC-5900) <cheryl.j.gramling at nasa.gov>
Sent: May 10, 2021 09:52
To: Lamy Alain <Alain.Lamy at cnes.fr>; moims-nav-exec at mailman.ccsds.org; Daniel Oltrogge <dan at comspoc.com>
Cc: Gramling, Cheryl J. (GSFC-5900) <cheryl.j.gramling at nasa.gov>
Subject: Re: [EXTERNAL] Re: [MOIMS-NAV-EXEC] leap second flagging

Ralph, Alain, All,

Thank you for the info and feedback.
One concern is to provide information content that encompasses existing messages in the SSA community. The Cislunar SSA Steering group felt it was important to be as explicit as possible, which aligns with the philosophy applied to other information in the OCM.

Here are two options the Cislunar SSA Steering Group identified as possibilities; this does not preclude other options:

OCM META provides for TAIMUTC_AT_TZERO and EOP_SOURCE.

  *   Option 1: Break up SSA Message for one before and one after Leap. Include OCM META flag to indicate leap occurred and # of integer seconds lept so user knows time offset of new message is bc of leap; message that follows the leap would have new TAIMUTC_AT_TZERO.
  *   Option 2: Use two subsequent Orbit Time History blocks, breaking across the leap, using ORB_PREV_ID to link the two blocks in sequence. OCM META include new field of LEAP_TIME followed by integer number of seconds applied at that time.


Regards,
Cheryl
-------
Cheryl Gramling
NASA/GSFC/590
Mission Engineering and Systems Analysis Division
Assoc. Chief for Technology
Goddard Senior Fellow
cheryl.j.gramling at nasa.gov<applewebdata://C044DB7D-E97B-4942-B8FB-61DE66DC36D1/cheryl.j.gramling@nasa.gov>
[O] 301-286-8002
[C] 240-328-5517


From: MOIMS-NAV-EXEC <moims-nav-exec-bounces at mailman.ccsds.org<mailto:moims-nav-exec-bounces at mailman.ccsds.org>> on behalf of Lamy Alain <Alain.Lamy at cnes.fr<mailto:Alain.Lamy at cnes.fr>>
Date: Monday, May 10, 2021 at 11:32 AM
To: "moims-nav-exec at mailman.ccsds.org<mailto:moims-nav-exec at mailman.ccsds.org>" <moims-nav-exec at mailman.ccsds.org<mailto:moims-nav-exec at mailman.ccsds.org>>, "Oltrogge, Daniel" <doltrogge at comspoc.com<mailto:doltrogge at comspoc.com>>
Subject: [EXTERNAL] Re: [MOIMS-NAV-EXEC] leap second flagging

Hi,

Just one thought:
I was wondering why these leap seconds would have to be in the message, as you can find them everywhere.
There is one case where there could some ambiguity:  for predictions when a planned leap second may be taken into account or not.
But I don’t know if that’s a good enough reason to have that the leap seconds in the message.

Alain

From: MOIMS-NAV-EXEC <moims-nav-exec-bounces at mailman.ccsds.org<mailto:moims-nav-exec-bounces at mailman.ccsds.org>> On Behalf Of Ralph.Kahle at dlr.de<mailto:Ralph.Kahle at dlr.de>
Sent: lundi 10 mai 2021 16:59
To: moims-nav-exec at mailman.ccsds.org<mailto:moims-nav-exec at mailman.ccsds.org>
Subject: [MOIMS-NAV-EXEC] leap second flagging

Dear all,
Regarding the flagging of leap seconds in orbit products please find an example below that we use at GSOC:

[cid:image001.png at 01D745C5.79BBBEA0]

Would something like this help the cislunar group and could be implemented into our messages?
Best,
Ralph

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